Microservices:A Taxonomy

Stefan Tilkovstefan.tilkov@innoq.com@stilkov

Microservices 2019

Microservices – Common Traits

• Focused on “one thing”

• Autonomous operation

• Isolated development

• Independent deployment

• Localized decisions

Example: Device Event Handling

• Incoming event validation

• Format transformation

• Fan-out event generation

• Aggregation

• StorageEvent Bus/Infrastructure

→FaaS

Pattern: FaaS (Function as a Service)

• As small as possible

• A few hundred lines of code or less

• Triggered by events

• Communicating asynchronously

Description: As seen on:• Any recent Fred George

talk

• Serverless Architecture

• AWS Lambda

Pattern: FaaS (Function as a Service)

• Shared strong infrastructure dependency

• Common interfaces, multiple invocations

• Application logic in event handler configuration

• Emerging behavior (a.k.a. “what the hell just happened?”)

• (Possibly) billed per request

• (Possibly) unpredictable response times

Consequences:

Example: Product Detail Page

• Core product data

• Prose description

• Images

• Reviews

• Related content Orchestration

→μSOA

Pattern: μSOA (Microservice-SOA)

• Small, self-hosted

• Communicating synchronously

• Cascaded/streaming

• Containerized

Description: As seen on:• Netflix

• Twitter

• Gilt

Pattern: μSOA (Microservice-SOA)

• Close collaboration – common goal

• Need for resilience/stability patterns for invocations

• High cost of coordination (versioning, compatibility, …)

• High infrastructure demand

• Often combined with parallel/streaming approach

• Well suited to environments with extreme scalability requirements

Consequences:

Antipattern: Decoupling Illusion

Stakeholder

Stakeholder

Stakeholder

Pattern: Autonomous Cells

Stakeholder

Stakeholder

Stakeholder

Biz

Dev

Ops

Biz

Dev

OpsBiz

Dev

Ops

Pattern: Autonomous Cells

Stakeholder

Stakeholder

Stakeholder

Biz

Dev

Ops

Biz

Dev

OpsBiz

Dev

Ops

Example: Logistics Application

• Order management

• Shipping

• Route planning

• Invoicing

Frontend→DDDD

Event Bus/Infrastructure

Pattern: DDDD (Distributed Domain-driven Design)

• Small, self-hosted

• Bounded contexts

• Redundant data/CQRS

• Business events

• Containerized

Description: As seen on:• (undisclosed)

Pattern: DDDD (Distributed Domain-driven Design)

• Loose coupling between context

• Acknowledges separate evolution of contexts

• Asynchronicity increases stability

• Well-suited for to support parallel development

Consequences:

That UI thing? Easy!

Assumption

Reality – Antipattern: Frontend Monolith

Example: E-Commerce Site

• Register & maintain account

• Browse catalog

• See product details

• Checkout

• Track status

→SCS

Pattern: SCS (Self-contained Systems)

• Self-contained, autonomous

• Including UI + DB

• Possibly composed of smaller microservices

Description: As seen on:• Amazon

• Groupon

• Otto.de

• https://scs-architecture.org

Pattern: SCS (Self-contained Systems)

• Larger, independent systems,including data + UI (if present)

• Able to autonomously serve requests

• Light-weight integration, ideally via front-end

• No extra infrastructure needed

• Well suited if goal is decoupling of development teams

Consequences:

Building Block0..1

*

One more thing …

One more thing …We love monoliths –so let’s build a lot of them!

Separateseparatethings

Join things that belong together

Stefan Tilkov @stilkovstefan.tilkov@innoq.comPhone: +49 170 471 2625

innoQ Deutschland GmbH

Krischerstr. 100 40789 Monheim am Rhein Germany Phone: +49 2173 3366-0

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@stilkovThat’s all I have. Thanks for listening!

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